Punctuation is the salt in the soup of writing. Without all those periods, commas, colons, brackets, quotation and question marks and so on, we'd have a hard time making sense of the words that come flying by. However, even though peppering texts with little ink spots is a common phenomenon, specific languages handle this in quite diverse ways.

Even languages with the same script may have differing conventions. ¿Or didn't you know of the inverted question mark that, quite conveniently, pre-announces an interrogative sentence in Spanish? And don't forget the French custom of leaving a space before an exclamation point, here -> ! Needless to say, Japanese has its own set of punctuation marks too, and a number of special rules regarding their usage.

Let's start with "。" (句点, kuten or マル, maru), the Japanese full-stop mark, and "、" (読点, tōten or just テン, ten), the Japanese comma. What makes things a bit confusing is that these two coexist with "." (ピリオド, piriodo) and "," (コンマ, konma), respectively. Use of these latter two is restricted to horizontally written text, whereas "。" and "、" can appear in both vertical and horizontal writing.